So-called ID cards such as member certificates and student certificates that indentify the bearers as particular persons have been hitherto used. Various personal data such as a photograph of the bearer's face, and an address, membership, or personal code number of the bearer are recorded in, or stuck on, such ID cards so that a person can be confirmed to be the person himself or herself.
Such ID cards satisfactorily function when they are used in normal forms. However, if, for example, they have been lost, the ID cards of this type, whose photograph can be peeled with ease and its mount and another photograph can be available in general, are sometimes misused, e.g., altered by replacing the photograph or forged through an illegal channel, causing social problems.
To cope with this, a measure has been hitherto taken, for example to affix a seal or stamp over the photograph of a face when the ID cards are prepared. In replacement thereof, it has become prevalent in recent years to record all the data such as the face and characters on a color photographic paper, a heat-sensitive color recording material or the like, and hold the color photographic paper between laminate materials not usually available, e.g. watermarked materials, to heat-bond the laminate materials with a hot melt or adhere them with a pressure-sensitive adhesive.
In this way, it is presently prevalent to prepare ID cards by laminating the color photographic paper, heat-sensitive color recording material or the like. This means, however, still can not effectively prevent the forgery or alteration of ID cards. That is to say, such light-sentive materials are commonly available, and hence even a nonprofessional can forge ID cards if, for example, a pattern of the desired ID card is previously prepared through any means, which is then photographed and printed in a given size. In the conventional methods of making the ID cards, forgery and alteration cannot be satisfactorily prevented, unsatisfactorily, and more effective means for preventing the forgery or alteration has been sought.
On the other hand, it is also common to keep a bar code or optically readable characters recorded on an ID card, and optically read these to judge the ID card. In this system of optically reading the information, ID cards operable in various spectral regions are used as described, for example, in JIS C6253-1983. In particular, however, the bar code or the characters read by an optical character reader (hereinafter "OCR") must have a sufficient light-absorbing ability to infrared light so that an OCR having spectral light mainly in infrared wavelength regions can be operated to perform normal reading.
In the ID cards, usually, photographs of the bearer's face are recorded, and are particularly required to be able to visually indentify the persons themselves with ease. Hence, for such identification, a color recording material with a high image quality may preferably be used at the part of a the photograph of face. The high image quality herein mentioned refers to a high resolving power as exemplified by a resolving power of about not less than 8 dots per 1 mm, and means that the recording material can continuously change its gradation or has a gradation of not less than 32 gradations, and preferably not less than 64 gradations.
Those preferably used as such recording materials include silver salt color recording materials employing a silver halide or those so called as sublimation dye thermal transfer recording materials.
The above silver salt color recording materials or sublimation dye thermal transfer recording materials, however, are comprised of a colorant which is a dye. Hence, they have insufficient absorbance to infrared light and therefore, in order to enable reading with an infrared OCR, it becomes necessary to record an image by a method that enables reading with the infrared OCR.
With such an aim, the present inventors have attempted various methods, where an image was recorded on a recording material on which a color image has been recorded, according to a method of recording characters capable of being read by the infrared OCR, and the resulting recording material was laminated on its surface with a laminate material to prepare an ID card. Nothing, however, was obtained without a high possibility of alteration (in other words, readiness in the peeling of laminate surfaces), and also with a high image quality for either the color image such as the photograph of a face or the characters to be read by an OCR.